Cutaneous angiolymphoid hyperplasia with high endothelial venules is characterized by endothelial expression of cutaneous lymphocyte antigen

T-Cell-Rich Angiomatoid Polypoid Pseudolymphoma: A Case Report and Comparison With Key Differential Diagnoses

T-cell-rich angiomatoid polypoid pseudolymphoma (TRAPP) is a rare and recently defined entity, conceptualized just over a decade ago. Recognition of TRAPP is important because it can be clinically and microscopically confused with low-grade cutaneous lymphomas and other vascular proliferations. We report a case of a 28-year-old male with a solitary 1.2 cm red polypoid papule on the middle posterior base of the neck. The histopathological examination revealed a well-circumscribed dermal nodular proliferation of banal-appearing lymphovascular spaces with plump endothelial cells. Immunohistochemical analysis showed a T-cell-rich infiltrate. The clinical-pathological differential diagnosis for TRAPP includes pyogenic granuloma, angiolymphoid hyperplasia (epithelioid hemangioma), acral pseudolymphomatous angiokeratoma of children, cutaneous lymphoid hyperplasia, and low-grade cutaneous lymphomas and lymphoproliferative disorders. We review the literature and discuss the key differentiating features between TRAPP and its common differential diagnoses.

Inflammatory lobular hemangioma: A vascular proliferation with a prominent lymphoid component. Review of a series of 19 cases

In the last 30 years, there has been a strong interest in vascular proliferations. Pyogenic granuloma was not only renamed lobular capillary hemangioma, but also the conceptual interpretation was also changed from an overgrowth of granulation tissue to a genuine hemangioma (or benign vascular neoplasm). We describe 19 cases of patients who presented clinically with a vascular lesion, characteristically a pyogenic granuloma or lobular hemangioma, where the histopathological findings led to the pathologic concern for a lymphoma of the skin. These benign lesions with a dense lymphoid infiltrate were further defined on the basis of different vascular and lymphoid immunohistochemical markers as inflammatory lobular hemangiomas. We propose that given the considerable histopathological overlap between acral pseudolymphomatous angiokeratoma, T-cell rich angiomatoid polypoid pseudolymphoma of the skin, and other designations of some of these vascular proliferations with a rich and dense lymphoid infiltrate, they might constitute a spectrum of vascular lesions with varying clinical presentations.

Expression of Peripheral Node Addressins by Plasmacytic Plaque of Children, APACHE, TRAPP, and Primary Cutaneous Angioplasmacellular Hyperplasia

High-endothelial venules are a common feature of 3 types of cutaneous pseudolymphomas: pretibial lymphoplasmacytic plaque (PLP) of children, acral pseudolymphomatous angiokeratoma of children (APACHE), and T-cell rich angiomatoid polypoid pseudolymphoma (TRAPP). In addition, primary cutaneous angioplasmacellular hyperplasia (PCAH) overlaps with these other 3 conditions. We intend to study the expression of peripheral node addressins in PLP, APACHE, TRAPP, and PCAH. We studied 1 case of PLP, 2 cases of APACHE, 2 cases of TRAPP, and 2 cases of PCAH. Immunostainings for MECA-79 and WT-1 were obtained in all cases. All cases showed a dense lymphohistiocytic dermal inflammatory infiltrate with abundant plasma cells. In addition, HEV were prominent in all cases. Cases of PLP, APACHE, and TRAPP expressed MECA-1. Cases of PCAH did not express MECA-1. Although PLP, APACHE, and TRAPP seem to fall under the same morphologic spectrum with different clinical representations, PCAH seems to be a different entity, with histopathologic peculiarities and a different immunophenotype.